Bug ID 1381901: Egress ARP requests are dropped on native-vlan interfaces on the BX520 blade

Last Modified: May 22, 2026

Affected Product(s):
F5OS Velos(all modules)

Fixed In:
F5OS-C 1.8.0

Opened: Oct 20, 2023

Severity: 2-Critical

Symptoms

On a VELOS chassis with BX520 blades, if an interface is configured for native vlan tagging (i.e. an untagged interface), small egress packets like ARP requests may be sent with a frame size smaller than the Ethernet minimum frame size of 64 bytes. Such frames are known as runts, and the peer device is likely to discard runt frames as an interface input error.

Impact

Failure to resolve MAC addresses using ARP requests.

Conditions

- BX520 blade. - Native vlan configured on the interface. - Egress ARP requests (or other egress frames that are smaller than or just barely larger than the Ethernet minimum frame of 64 bytes.)

Workaround

None

Fix Information

For frames egressing an interface on a vlan configured as a native vlan, the FPGA will add padding to the frame if its size is less than 64 bytes after the vlan tag is stripped.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips